Stock Superglide tanks

[kd]

Way wider.

[Burnout]

On a 3.5 tank the caps sit a sort of an angle,
on a 5 gal the caps are on top of the tank.

[billbuilds]

The 3.5 and the 5 gallon tanks look the same from the side. Look at both from the top and you will see the difference. The 5s are wider than the 3.5s.

      When viewed from the side at the same height the 5 gallon tanks cover more of the rocker box than the 3.5 gallon. Yes I know they're wider. Owner's manual and parts book show that the FXEF came stock with 3.5 gallons tanks but there's no way on God's green earth that those tanks on the FXEF that I posted a photo of from the 1980 owners manual are 3.5 gallon. 

[One4Tone]

..there was a guy in town named Bob...must have weight in at  460 lbs. he walked in a dealership in town back in the late 70's and they sold him a Fatbob...guess what his nickname became?..He didn't know much and with his weight the bike looked small. He rode that bike for 35 years..he had it lowered so he could get his leg over it. I think he did it with a longer swing arm and angular shocks...he was dam proud of that bike and you allways found him hangin around donut shops all over town. He putted around and was allways at the back of the pack when a bunch of us went riding. 50 miles an hour was as fast as old Fatbob would ride...main rhing is he allways had a smile while riding...maintain